Pressure difference sensors for use in industrial measurements technology are sufficiently known from the state of the art. Such are usually composed of a micromechanically manufactured, pressure difference measuring cell based on a semiconductor material. The pressure difference measuring cell is arranged between two stiffening elements. For obtaining a pressure measurement signal, the pressure difference measuring cell is fed a first pressure and a second pressure. To this end, each stiffening element has a duct with a 90° change of direction in it. On one end of a stiffening element, its duct is in communication with the pressure difference measuring cell. The other end communicates with a capillary tube. The capillaries, in turn, connect the stiffening element with a platform, which serves for connecting the pressure difference measuring cell to a process. For this, the platform includes two isolating diaphragms, each of which isolates a hydraulic path formed from the platform via the capillaries and the stiffening elements to the pressure difference measuring cell from the medium to be measured. Via each hydraulic path, the pressure applied against its isolating diaphragm is led to the pressure difference measuring cell, in order to generate the pressure measurement signal.
In the case of the pressure difference sensors known from the state of the art, the capillaries are usually embodied as straight tubes extending between the stiffening elements and the platform. Materials used for pressure difference sensors known from the state of the art include, for the platform, a stainless steel (VA steel), for the capillaries, a Kovar alloy, and, for the stiffening elements, a ceramic.
This matter of construction has the disadvantage that, in the case of temperature changes, the platform expands significantly more than the composite of stiffening element and pressure difference measuring cell, since the thermal expansion coefficient of the platform material is significantly greater than that of the material of the pressure difference measuring cell, and the material of the stiffening element. The expansion differences lead, in turn, to an occurrence of a bending loading of the pressure difference measuring cell. The bending loading can lead to a corruption of the pressure measurement signal and, thus, to a limiting of accuracy and/or long term stability. Moreover, the bending loading can, in the worst case, lead to a destruction of the pressure difference measuring cell or another part of the pressure difference sensor.